Don't constantly recreate index buffers.

Don't constantly recreate index buffers.

Recreating index buffers for closing loops can take a long time, so use a streaming index buffer instead.

BUG=
TEST=

Committed: http://code.google.com/p/angleproject/source/detail?r=625

[John Bauman, 2011-04-28 02:13:36]

Split out the index buffer part.

[dgkoch, 2011-04-28 03:07:31]

minor nit re sizeof calculations. LGTM after those are fixed.

I didn't realize the canvas implementation was using line loops.  Good to have
this fixed then.

http://codereview.appspot.com/4438080/diff/1/src/libGLESv2/Context.cpp
File src/libGLESv2/Context.cpp (right):

http://codereview.appspot.com/4438080/diff/1/src/libGLESv2/Context.cpp#newcod...
src/libGLESv2/Context.cpp:2765: const int spaceNeeded = 2 * sizeof(int);
technically this should probably be "2 * sizeof(unsigned int)"

http://codereview.appspot.com/4438080/diff/1/src/libGLESv2/Context.cpp#newcod...
src/libGLESv2/Context.cpp:2786: const int spaceNeeded = 2 * sizeof(short);
this should be "2 * sizeof (unsigned short)"

[nicolas, 2011-04-28 10:34:09]

FYI, I've created a Wiki page to document the Buffer implementation
(http://code.google.com/p/angleproject/wiki/BufferImplementation). Note that it
likely needs updating after committing these changes.